Methylation-independent binding to histone H3 and cell cycle-dependent incorporation of HP1beta into heterochromatin.
J Biol Chem
; 281(20): 14350-60, 2006 May 19.
Article
en En
| MEDLINE
| ID: mdl-16547356
ABSTRACT
We have examined HP1beta-chromatin interactions in different molecular contexts in vitro and in vivo. Employing purified components we show that HP1beta exhibits selective, stoichiometric, and salt-resistant binding to recombinant histone H3, associating primarily with the helical "histone fold" domain. Furthermore, using "bulk" nucleosomes released by MNase digestion, S-phase extracts, and fragments of peripheral heterochromatin, we demonstrate that HP1beta associates more tightly with destabilized or disrupted nucleosomes (H3/H4 subcomplexes) than with intact particles. Western blotting and mass spectrometry data indicate that HP1beta-selected H3/H4 particles and subparticles possess a complex pattern of posttranslational modifications but are not particularly enriched in me3K9-H3. Consistent with these results, mapping of HP1beta and me3K9-H3 sites in vivo reveals overlapping, yet spatially distinct patterns, while transient transfection assays with synchronized cells show that stable incorporation of HP1beta-gfp into heterochromatin requires passage through the S-phase. The data amassed challenge the dogma that me3K9H3 is necessary and sufficient for HP1 binding and unveil a new mode of HP1-chromatin interactions.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Proteínas Cromosómicas no Histona
/
Heterocromatina
/
Histonas
Límite:
Animals
/
Humans
Idioma:
En
Revista:
J Biol Chem
Año:
2006
Tipo del documento:
Article
País de afiliación:
Grecia